Feeding set adaptor

ABSTRACT

A feeding set adaptor and related system for delivering solutions utilize a feeding set adaptor which engages a pump engaging portion of an infusion set and the feeding set adaptor structure to provide monitoring portions for detecting pressures within the infusion set, a sample cell for determining the presence of air within an infusion set, and an anti-freeflow device for selectively preventing freeflow through the infusion set. The feeding set adaptor is configured for mounting on an infusion pump which moves solution through the infusion set for delivery to a patient.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to systems for feeding solutions topatients. More particularly, the present invention relates to a feedingset adaptor which is used in association with a medical solution pump.The pump and an infusion set which is acted on by the pump typicallyform a system for the monitoring of fluid pressures, for bubbledetection and for selective flow occlusion of solutions being fed to apatient. Specifically, the invention relates to an adaptor which is usedto connect various parts of an infusion set and to integrate them withthe pump to enable the monitoring of fluid pressures, the detection ofbubbles, and the selective occlusion of fluid flow to prevent freeflowconditions.

[0003] 2. State of the Art

[0004] There are numerous situations in which a solution must be fed toa patient over a period of time. In some situations, the solution isprovided directly into the blood stream of the patient. Saline solutionsand medications supplied in such a manner are typically referred to asparenteral solutions.

[0005] In contrast to a parenteral system, an enteral feeding system isused to provide nutrient solutions to patients who, for one reason oranother, are unable to eat for themselves. Such a system typicallyincludes a pump which is attached to an input tube connected to a supplycontainer and to an output tube which is connected to a patient. Thepump draws nutrient solution from the supply container and delivers thesolution to the patient. By adjusting the number of rotations of themotor, or the frequency of rotations, in the pump, an enteral feedingpump can adjust its output to deliver a predetermined amount of nutrientsolution (or even medication) at a desired rate.

[0006] A significant problem with many currently available enteralfeeding systems, is that the intake and output tubes may becomeoccluded. Unlike parenteral solutions, enteral feeding solutions have arelatively high viscosity, as they must carry sufficient nutrition tosustain the patient. Occlusion can occur, for example, if a fibroussubstance is included in the enteral feeding solution and somehowcombines to interfere with flow through the tube. Occlusion can alsooccur if a tube is bent sufficiently to interfere with flowtherethrough, or if a roller clamp (as is commonly used for intravenousapplications) is not sufficiently opened. Because of the viscosity ofthe solution, the amount of kinking of the tube or other interferencerequired to interfere with solution flow is significantly less than thatrequired in a parenteral infusion set.

[0007] If the intake tube becomes occluded, insufficient solution may besupplied to the pump, and thus to the patient. If the output tubebecomes occluded, the flow of solution may be blocked, or the solutionmay be delivered suddenly at unusually high pressures. Additionally,medical personnel may fail to notice that the supply container is out ofsolution, or may not properly mount the intake and/or output tubes inthe pump, thereby preventing the proper amount of solution from beingdelivered to the patient. Any of these scenarios can have tragicconsequences if allowed to continue for a prolonged period of time.

[0008] Yet another concern with enteral feeding systems is that ofviscosity of the solution and viscosity changes as a container full ofsolution is pumped to a patient. Knowing the viscosity of the fluidbeing pumped through the enteral feeding system is important becausedifferent viscosities are pumped at different rates by the enteralfeeding pump. For example, a lower quantity of a highly viscous solutionwill be pumped by a given number of rotations of the enteral feedingpump motor than will be moved by the same pump when the solution has lowviscosity. In other words, the amount of solution fed to the patient candiffer substantially depending on the solution's viscosity. Thus, unlessthe pump is able to accurately determine and compensate for viscositychanges in the solution (i.e. by increasing or decreasing the rotationsof the pump rotor in a given period of time), it is difficult to knowexactly how much of the solution has been fed to the patient.

[0009] Yet another problem which is of concern during the administrationof enteral feeding solutions is the presence of air bubbles. While verysmall air bubbles will not cause harm, large bubbles entering the bloodstream can cause serious medical complications and even death. Thus, itis important to monitor the solution to ensure that any bubbles presentdo not exceed the desired threshold.

[0010] Still another problem which is present in enteral feedingsystems, and the like, is freeflow. Often, the infusion set is placed ina free standing arrangement in which gravity forces the solution intothe patient. The rate at which the solution enters the patient can beroughly controlled by various clamps, such as roller clamps, which arecurrently available on the market.

[0011] In many applications, it is necessary to precisely control theamount of solution which enters the patient. When this is the case, aregulating device, such as an enteral feeding pump, is placed along theinfusion set to control the rate at which the solution is fed to thepatient. In applications where a pump, etc., is used, the clamps used toregulate flow are typically opened to their fullest extent to preventthe clamp from interfering with the proper functioning of the pump. Theclamp is opened with the expectation that the enteral feeding pump willcontrol fluid flow through the infusion set.

[0012] It is not uncommon, for emergencies or other distractions toprevent the medical personnel from properly loading the infusion set inthe enteral feeding pump. When the infusion set is not properly loadedin the pump and the clamp has been opened, a situation known as freeflowoften develops. The force of gravity causes the solution to flow freelyinto the patient unchecked by the pump or other regulating device. Undera freeflow condition, an amount of solution many times the desired dosecan be supplied to the patient within a relatively short time period.This can be particularly dangerous if the solution contains potentmedicines and/or the patient's body is not physically strong enough toadjust to the large inflow of solution.

[0013] Numerous devices have been developed in an attempt to preventfree flow conditions. Such devices, however, typically add significantlyto the overall cost of the infusion set and some provide only marginalprotection against free flow. Thus, there is a need for a device thatprevents a freeflow condition while allowing controlled flow through theinfusion set. There is also a need for such a device which preventsfreeflow if an infusion set is not properly mounted in a pump or otherregulating means. Furthermore, there is a need for a device whichprevents freeflow and which is inexpensive and easy to use.

[0014] The fluid flow monitoring mechanism disclosed in U.S. Pat. No.5,720,721 and the anti-freeflow mechanism described in U.S. Pat. No.5,704,584 (both of which are expressly incorporated herein) provided asignificant improvement in monitoring for enteral feeding pumps and incontrol of freeflow situations.

[0015] As shown in FIG. 1A, the pump taught in U.S. Pat. No. 5,720,721uses two pressure sensors to monitor viscosity and occlusions, and toenable the enteral feeding pump to compensate for the varying amount ofsolution which will pass through the pump with each rotation of therotor. The pressure sensors engage the elastic tube of the infusion setand monitor changes in the strain on the infusion set by occlusions andviscosity changes. The strain information can then be processed by thepump and adjustments made to the number of rotations of the pump rotorto compensate. In the event that the occlusion is too severe tocompensate by modification of the rotor rotations, the pump is shut downand an alarm signal generated so that replacement tubing may beprovided.

[0016] Also included was an air detector which was disposed in the pump.The air detector was disposed in communication with the pump and usedultrasonic energy to determine if bubbles were present in the conduit.

[0017] While the pressure sensor system of U.S. Pat. No. 5,720,721 is asignificant improvement over the art, it does have limitations. Thepressure sensors described in the '721 patent are relatively expensiveand must be properly mounted in the pump. Additionally, the personloading the pump must make sure that the upstream and downstreamportions of the infusion set are properly loaded in the pump housing sothat they engage the pressure sensors in the proper manner. Failure toproperly load the infusion set can interfere with the functioning of thepressure sensors. In particular, if the clinician overly stretches thetubing as he or she wraps it around the pump, the tube on one side ofthe pump rotor will be stretched to a greater degree than the opposingside. This, in turn, can effect pump accuracy if too severe.

[0018] One manner for decreasing the costs of pressure sensors is to usean optical sensors. While there are several methods for using opticalsensors to determine the presence of occlusions, each has significantdrawbacks. Some methods only allow the mechanism to determine when thepressure exceeds a certain threshold. This is done by detecting when theexpanding tube of the infusion set engages a surface, thereby modifyingreflection or refraction of light. Other methods require complexcalculations of refraction indexes or otherwise provide relativelylimited information on small pressure changes. Additionally, somemethods can vary based on the material from which the infusion set isformed, or based on whether the tube of the infusion set is opaque ortransparent.

[0019] In addition to the above, many mechanisms for monitoring pressurewithin an infusion set lack an inherent failure detector. For example,if a sensor is configured to sense only when the expanding infusion settube engages a transparent surface, the failure to record a reflectedsignal may mean that the tube has not expanded. In certain situations,however, the lack of reflected signal could also mean that the sensorhas failed and is either not sending the signal or is not receiving thereflected signal.

[0020] In addition to the concerns with pressure sensing technology ofthe prior pumps, the pumps also used ultrasonic technology for bubbledetection. While this technology is highly accurate, it is alsoexpensive. An ultrasonic sensor can cost as much as 50 times as much asan optical sensor.

[0021] In addition to the above, the anti-freeflow technology discussedin U.S. Pat. No. 5,704,584 has limitations. While the occluder mechanismworks well, it is relatively expensive to form a separate mechanism toselectively stop flow through the infusion set. A separate pinch clipoccludes such as that shown in FIG. 1B can add fifteen to twenty percentto the cost of an infusion set. While the cost per unit is rather small,daily replacement of the infusion set can add up to significant costs.In a highly competitive medical environment, even a few cents per unitcan dramatically effect sales quantities.

[0022] Thus, there is a need for a mechanism which can enable improvedpressure monitoring, improved air detection and improved flow occlusion.Such a mechanism should be relatively inexpensive and should lessen thelikelihood of errors in use of the pump and infusion set. Furthermore,it should enable the use of infusion sets made from a variety ofmaterials.

SUMMARY OF THE INVENTION

[0023] Thus, it is an object of the present invention to provide amechanism which allows improved method monitoring viscosity and/orocclusions in an infusion set.

[0024] It is another object of the present invention to provide such amechanism which facilitates the monitoring of viscosity and occlusionswith an optical sensor system.

[0025] It is another object of the present invention to provide amechanism which facilitates the optical monitoring of solution todetermine the presence of bubbles in the solution.

[0026] It is another object of the present invention to provide amechanism which prevents free flow through an infusion set unless fluidflow through the infusion set is being driven by the pump.

[0027] It is yet another object of the present invention to provide anintegrated adaptor which is disposed along an infusion set whichfacilitates pressure monitoring, bubble monitoring and an anti-free flowdevice.

[0028] The above and other objects of the present invention are realizedin specific illustrated embodiments of a feeding set adaptor configuredfor attachment to an upstream portion, a down stream portion and a pumpengaging portion of an infusion set.

[0029] In accordance with one aspect of the invention, the feeding setadaptor is attached to a flexible tube which forms the pump engagingportion of the infusion set. The flexible tube is mounted to the adaptorin such a manner that the tube is not disproportionately stretched oneither side of the pump mechanism when it is loaded on the pumpmechanism.

[0030] In accordance with another aspect of the invention, the flexibletube of the infusion set attached to the feeding set adaptor has atleast one monitoring portion which is held by the adaptor to preventstretching of the tube. The monitoring portion is disposed adjacent asensor which allows the pump to monitor pressure within the tube.Preferably, this is done by an optical sensor which is positioned tomonitor the diameter of the tube. By sensing changes in the diameter ofthe tube, the pump can determine the pressure within the tube. If thepressure sensed is above or below predetermined thresholds, the pump candetermine that there is an occlusion and will generate an alarm.

[0031] In a preferred embodiment, the flexible tube is secured formonitoring both upstream and downstream from the pump rotor (or otherpump mechanism). Thus, the pump can monitor upstream and downstreamocclusions. The pressure monitoring can also be used in conjunction withmovement of the pump mechanism to more accurately determine solutionflow through the pump system.

[0032] In a preferred embodiment, the feeding set adaptor is configuredto hold the tube in such a position that the tube neither obstructs alllight flow nor allows complete light flow between the two sides of theoptical sensor. Between the two extremes of receiving a full opticalsignal and no optical signal, the signals generated by the opticalsignal receiver indicate the extent to which the optical signal sent bythe optical signal emitter have been obstructed by the tube. If,however, a full reading is received, the pump can indicate that thefeeding set adaptor and the associated tube have not been properlymounted in the pump. In contrast, if no reading is received, the pumpcan generate an alarm indicating that the sensor is malfunctioning, orthat the infusion set tube has expanded well beyond the desiredthreshold.

[0033] In accordance with another aspect of the invention, the feedingset adaptor includes a sample cell through which solution being pumpedby the pump is passed. The sample cell is configured for monitoring thesolution to determine the presence of bubbles. Preferably, the samplecell has a pair of angled sidewalls. The angled sidewalls are preferablydisposed at an angle of 47 to 70 degrees from each other, depending onthe indices of refraction of the material used, and are most preferablyangled 50 to 60 degrees from one another.

[0034] The sample cell is configured to fit into a void on a housingdisposed adjacent to an optical sensor. Light from the optical sensorpasses through the housing and the sample cell in such a manner that itis refracted in one direction if the sample cell is full of liquid andanother angle if a bubble is present in the sample cell. Thus, the pumpis able to monitor for bubbles and to make appropriate corrections inpump flow rate or to generate an alarm if the amount of air present inthe solution exceeds desired thresholds.

[0035] In accordance with one aspect of the invention, an occluder isdisposed within the infusion set. The occluder is configured to preventfree flow of fluids in the infusion set past the occluder. The occluderis also configured, however, to selectively allow solutions to pass bythe occluder which are pumped by an enteral feeding pump and the like.

[0036] In accordance with another aspect of the invention, the feedingset adaptor includes an occluder which prevents fluid flow through theinfusion set when the infusion set has not been disposed in properengagement with the pump mechanism of the infusion pump, thereby givingcontrol of fluid flow through the infusion set to the pump.

[0037] In one embodiment of the invention, the occluder is formed by astop attached to the feeding set adaptor and placed in the tubing of theinfusion set. The stop limits flow through the tube by limiting flowaround and/or through the stop when the solution is subject to flow dueto gravity. However, when greater pressures are placed on the solution,such as those produced by a pump, the solution is able to flow aroundand/or through the stop, thereby delivering the solution to the patient.

[0038] In accordance with another embodiment of the present invention,an occluding valve is formed as part of the feeding set adaptor and isdisposed in the infusion set. The valve prevents free flow through theinfusion set due to gravity, while allowing controlled flow of solutionthrough the infusion set.

[0039] In accordance with another aspect of the invention, the occluderis configured to stop fluid flow until the infusion set has beenproperly loaded into a control mechanism such as a pump. Once properlyplaced, the interaction between the occluder and the infusion seteffectively opens the infusion set to allow solution to flowtherethrough.

[0040] In accordance with still yet another aspect of the invention, aplurality of the aspects discussed above are integrated into a singlefeeding set adaptor. By integrating the various aspect discussed above,the health care professional or patient who loads the pump with theinfusion set can be assured that the safety and monitoring aspectsdiscussed above are being accomplished without the need to checkmultiple systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of theinvention will become apparent from a consideration of the followingdetailed description presented in connection with the accompanyingdrawings in which:

[0042]FIG. 1A shows a top view of an enteral feeding pump housing formedin accordance with the principles of the prior art;

[0043]FIG. 1B shows a top view of a top of an enteral feeding pumphousing and a pinch clip occluder formed in accordance with theprinciples of the prior art;

[0044]FIG. 2A shows a top perspective view of a feeding set adaptorconfigured in accordance with the principles of the present invention;

[0045]FIG. 2B shows a bottom perspective view of the feeding set adaptorshown in FIG. 2A;

[0046]FIG. 2C shows a side view of the pump engaging portion of theinfusion set;

[0047]FIG. 3 shows a bottom view of an enteral feeding set adaptorhaving the pump engaging portion of the infusion set disposed thereinfor mounting on an infusion pump in accordance with the principles ofthe present invention;

[0048]FIG. 4 shows a fragmented perspective view of an infusion set anda perspective view of a feeding set adaptor and an enteral feeding pumpmade in accordance with principle of the present invention;

[0049]FIGS. 5 and 5A show close-up, cross-sectional views of theadaptor, flexible tubing and portion of the enteral feeding pumprelating to the pressure monitoring mechanism associated with feedingset adaptor;

[0050]FIGS. 6 and 6A show a close-up, cross-sectional view of theadaptor and the enteral feeding pump portions relating to the detectionof air bubbles passing through the infusion set;

[0051]FIGS. 7 and 7A show close-up, cross-sectional views of the adaptorand infusion set relating to the anti-freeflow mechanism of the presentinvention;

[0052]FIG. 7B shows a close-up, cross-sectional view of the adaptor,infusion set and enteral feeding pump providing an alternate embodimentof the anti-freeflow mechanism of the present invention; and

[0053]FIG. 7C shows a close-up, cross-sectional view of yet anotherembodiment of the anti-freeflow mechanism of the present invention.

DETAILED DESCRIPTION

[0054] Reference will now be made to the drawings in which the variouselements of the present invention will be given numeral designations andin which the invention will be discussed so as to enable one skilled inthe art to make and use the invention. It is to be understood that thefollowing description is only exemplary of the principles of the presentinvention, and should not be viewed as narrowing the pending claims.

[0055] Referring to FIG. 1A, there is shown a top view of an enteralfeeding system taught in U.S. Pat. No. 5,720,721. The enteral feedingsystem, generally indicated at 4, has a delivery set 8 including anintake (upstream) tube 10 and an output (downstream) tube 14 connectedtogether by a pair of connectors 18 and a pump tubing segment within anenteral feeding pump 20. The position of the pump tubing segmentdisposed inside of the pump 20 is represented by the dashed lines 16.

[0056] The enteral feeding pump 20 includes a housing 24 with aconventional motor unit, generally indicated at 28. The motor unit 28includes a rotor 30 with a plurality of peristaltic rollers 34 disposedabout an exterior of the rotor to move liquid through the enteralfeeding pump 20. The rotor 30 is connected by a shaft 32 to a motor (notshown). The section 38 of the pump tubing segment 16 is disposed aboutthe rotor 30 and rollers 34 and is usually made of a flexible siliconematerial. Rotating the rotor 30 in the direction indicated by the arrowsdirectionally squeezes the tube section 38 and causes solution to bepushed through the output tube 14.

[0057] Also shown in FIG. 1 is an air detector 40 provided in a proximalposition (upstream) from the motor unit 28 along the intake tube 10 towarn medical personnel of an empty supply container or a large bubble inthe infusion set.

[0058] In addition to these elements, the enteral feeding pump 20 of thepresent invention includes a pair of pressure sensors 50. In a preferredembodiment, two pressure sensors 50 a and 50 b are disposed along thepump tubing segment 16 adjacent the intake/output tubes to 1) ensurethat the tubes are properly mounted in the pump 20; 2) monitor anychanges in viscosity which are significant enough to alter the amount ofliquid moved by each rotation or partial rotation of the rotor 30; and3) detect any occlusions in the intake tube 10 or the output tube 14 ofthe delivery set 8. A retention plate 54 (FIG. 1) is attached to thehousing 24 by a screw 58 to hold the pressure sensors 50 a and 50 b inplace.

[0059] While the pressure sensor system of U.S. Pat. No. 5,720,721 was asignificant improvement over the art, it does have limitations.Specifically, the pressure sensors are relatively expensive and theaccuracy depends on the proper loading of the tube in the pump.Additionally, the air detector used ultrasonic energy and ultrasonicsensors are relatively expensive. Furthermore, as the health careprofessional or patient loaded the pump, he or she could effect therelative stretching of the tube as it was wrapped around the rotor ofthe pump. This, in turn, could effect the strain detected by thepressure sensors.

[0060] In addition to the above, the pump required some sort of antifree flow mechanism to prevent solution from running through theinfusion set when the tube was not securely engaging the pump rotor.Thus, a pinch clip occluder, as shown in FIG. 1B at 96 was taught inU.S. Pat. No. 5,704,584. While the pinch clip occluder shown is highlyeffective, it is relatively expensive compared to the cost of theinfusion set.

[0061] Turning now to FIGS. 2A and 2B there are shown a top perspectiveview and a bottom perspective view of a feeding set adaptor, generallyindicated at 100, which improves upon the prior art. The feeding setadaptor has a connector portion 104 having a first connector 108 and asecond connector 112. The first connector portion 104 also preferablyhas a small handle 116 which can be used to pull the feeding set adaptor100 from a pump if necessary.

[0062] The first connector 108, a functional proximal end 108 a whichengages the functional distal end of an inflow line (not shown) of aninfusion set. The opposing end of the infusion line is typicallydisposed in communication with a fluid container which holds thesolution being delivered to the patient. The first connector 108 willtypically be approximately the same diameter as the inflow tube, and theinflow tube is mounted on the first connector by being stretched overthe distal end 108 a of the connector.

[0063] The first connector 108 also has a functional distal end 108 b.The distal end 180 b is preferably configured with an annular barb 108 cand a neck portion 108 d positioned proximally from the annular barb.The annular barb 108 c and neck portion 108 d are used to secure a pumpengagement portion of the infusion set, which is discussed belowregarding FIG. 2C. As shown in FIG. 1, the distal end 108 b of the firstconnector 108 has conduit 120 which is generally triangular.

[0064] Disposed within the first connector 108 is a sample cell 124. Aswill be discussed in additional detail below, the sample cell 124 isused in conjunction with an optical sensor (not shown) to opticallydetermine the presence of air bubbles within the conduit 120. The samplecell 124 is preferably triangular and has sidewall which are offset fromone another at an angle of between about 47-70 degrees. In a presentlypreferred embodiment, the sample cell 124 is made with a wall whichforms an equilateral triangle with two sidewalls being disposed at anangle of about 50 to 60 degrees. Such an angle allows light emitted fromthe optical sensor to be refracted in a first direction if the conduit120 is filled with liquid, and a second direction if the conduit has anyappreciable amount of air. The refracted light, or relative absencethereof, indicates the relative size of the air bubble. A more detaileddiscussion regarding bubble detection is found in U.S. patentapplication Ser. No. ______ (Co-filed herewith and identified asAttorney Docket No. 0906.ZEVX.PT) which is expressly incorporatedherein.

[0065] Disposed functionally distally (i.e. downstream) from the distalend 108 b of the first connector 108 is a first tube engagement member130. The first tube engagement member 130 preferably includes a wall 132having generally U-shaped opening 134 which is sized to receive the pumpengagement portion of the infusion set.

[0066] The first tube engagement member 130 also preferably includes apair of flanges 138 which extend inwardly to partially obstruct theopening and to form a recess which receives a collar (see FIG. 2C) ofthe pump engagement portion of the infusion set.

[0067] The pump engagement portion of the infusion set, which isgenerally indicated at 200 in FIG. 2C includes an elongate tube portion204. The tube portion 204 is preferably a flexible tube made from amedical grade material, such as silicone. Such tubes are commonly usedin enteral feeding pumps.

[0068] Unlike most enteral feeding pump tubes, however, the tube portion204 has a first fitting 208 disposed at a functionally proximal end(i.e. upstream). The first fitting 208 is preferably used by a machineto secure the tube portion 204 and to attach a proximal end 204 a of thetube to the distal end 108 b of the first connector 108.

[0069] Disposed distally from the first fitting 208 is a first abutmentmember 212, which is preferably in the form of a collar 216. (In lightof the present disclosure, those skilled in the art will appreciate thatnumerous other abutment configurations could be used to secure the tubeportion 204 as described). The abutment member 212 in particular, andthe collar 216 specifically, are designed to nest in the recess 142against the wall 132 of the first tube engagement member 130. Whennested in the recess, the tube portion 204 which is proximal to thecollar 216 is held taut between the first tube engagement member 130 andthe first connector 108.

[0070] When the pump engaging portion 200 of the infusion set isattached to the distal end 108 b of the first connector 108, it isstretched slightly until the collar 216 is slightly passed the flanges134 of the first tube engagement member 130. The tube portion 204 isthen moved between the flanges 134 and the tube released so thecontraction of the tube pulls the collar 216 into the recess 142.

[0071] Disposed distally from the first tube engagement member 130 is asecond tube engagement member 150. As with the first tube engagementmember 130, the second tube engagement member preferably includes a wall152 with a generally U-shaped opening 154 which is sized to receive thepump engagement portion of the infusion set.

[0072] The second tube engagement member 150 also preferably includes apair of flanges 158 which extend inwardly to partially obstruct theopening and to form a recess 162 which receives an abutment member 220,which is preferably in the form of a collar 224 (FIG. 2C). (Thoseskilled in the art will appreciate that other abutment members such asarms, nubs or flanges could also be used). As shown in FIG. 2B, therecess 162 preferably faces the recess 142 in the first tube engagementmember and works with the collar 224 to prevent the portion of the tubeportion 204 disposed proximally adjacent to the collar from beingstretched to any significant degree when the central working portion 230of the pump engaging portion 200 of the infusion set. Likewise, when thepump rotor rotates, the stretching of the tube portion 204 proximallyfrom the collar 224 is minimized.

[0073] Because the proximal collar 216 prevents proximal movement andthe distal collar 224 prevents distal movement, the portion 234 of thetube disposed therebetween is held against movement, this portion formsa relatively isolated monitoring portion 234.

[0074] To properly determine the flow through an infusion set, and toproperly determine the presence of occlusions in an infusion set, it isadvantageous to monitor pressure within the infusion set. This can beaccomplished either by pressure sensors, such as those discussed in U.S.Pat. No. 5,720,721, or by an optical detector as discussed in co-pendingU.S. patent application Ser. No. ______ (Filed concurrently herewith andidentified as attorney docket no. 0908.ZEVX.PT, and which is expresslyincorporated herein). As is explained more fully in the co-pendingapplication, the pressure in the infusion set can be determined byhaving the tube occlude light in an optical sensor. As the tube expandsdue to increased pressure or contracts due to a vacuum caused byocclusions, etc., the amount of light which is received by the opticalsensor changes, thereby indicating the change in pressure in the tube.

[0075] Using the diameter of the tube to determine pressure can providehighly accurate readings. However, the accuracy of such readings isdiminished if the tube is being stretched inconsistently because havingthe tube under tension will change the extent to which it expands andcontracts due to pressure changes. This is resolved in the presentinvention by the first and second tube engagement members 130 and 150and the abutment members 212 and 220 (collars 216 and 224). Thesestructures interact so that the monitoring portion 234 is heldrelatively unstretched, regardless of tension from either side. Becausemost of the tension will occur due to loading the central workingportion 230 of the pump engagement portion 200 and rotation of the pumprotator, the second tube engagement member 150 is more critical than thefirst pump engagement portion. Thus, it will be appreciated that thefirst pump engagement portion 130 could be omitted while maintainingmost of the benefits of the present invention.

[0076] The feeding set adaptor 100 also includes a third tube engagementmember 170. The third tube engagement member preferably includes a wall132 defining a generally U-shaped opening 174 which is sized to receivethe pump engagement portion of the infusion set. The third tubeengagement member 170 also preferably includes a pair of flanges 178which extend inwardly to partially obstruct the opening and to form arecess 182 which receives an abutment member 240, which is preferably inthe form of a collar 244 (FIG. 2C).

[0077] As shown in FIG. 2B, the recess 182 preferably faces in the samedirection as the recess 162 in the second tube engagement member 150.When the pump engaging portion 200 of the infusion set is properlyloaded, the collars 224 and 244 are disposed in recesses 162 and 182.This substantially isolates the central working portion 230 and preventsrotation of the pump rotor from causing tension either upstream ordownstream from the collars 224 and 244, respectively.

[0078] The feeding set adaptor 100 further comprises a fourth tubeengagement member 186. The fourth tube engagement member 186 preferablyincludes a wall having a generally U-shaped opening 188. A pair offlanges 190 are disposed adjacent the U-shaped opening to partiallyobstruct the opening and to form a recess 192. The pump engaging portion200 of the infusion set includes an abutment member 250 in the form of acollar 254 which is configured to nest in the recess 192.

[0079] The recess 192 of the fourth tube engagement member 186 faces thesame direction as first tube engagement member 130 and the third andfourth tube engagement members act together in the same manner as thefirst and second engagement members to isolate a second monitoringportion 260 on the tube 204. Thus, the infusion pump is able tooptically monitor both the upstream pressure between the first andsecond engagement members 130 and 150, and the downstream pressurebetween the third and fourth engagement members. Thus, the pump canreadily determine if an occlusion in the infusion set is inhibitingdelivery of solution to the patient.

[0080] The feeding set adaptor 100 also includes an anti-freeflowmechanism 300. As shown in FIGS. 2A and 2B, the anti-freeflow mechanism300 is in the form a small ball 304 which is attached to the proximal(i.e. upstream) end 112 a of the second connector 112 by a small wall308. The wall 308 is configured to provide minimal resistance to flow ofliquid into the proximal end 112 a of the second connector 112.

[0081] In order to prevent freeflow through the infusion set, theanti-freeflow mechanism 300 is inserted into the distal end 204 b of thetube portion 204. The tube portion 204 is then advanced until the distalend 204 b passes over an annular barb 112 c and rests on the neck 112 dof the second connector 112. A second fitting 268 on the tube portion204 is typically used so that a machine can readily mount the distal end204 b of the tube portion 204 on the proximal end 112 a of the secondconnector 112.

[0082] Once the tube is in place, the small ball 304 will preventsolution flow through the tube portion 204 unless the solution is undersufficient pressure. Thus, the small ball 308 will prevent flow throughthe tube portion 204 if the solution is simply subject to gravity.However, if the solution is placed under sufficient pressure, theflexible material (typically silicone) of the tube portion 204 willexpand and allow solution to flow past the small ball 308. This isaccomplished as the pump drives solution through the infusion set. Ifthe pump is not properly engaging the central working portion 230 of thetube portion 204, there will not be enough pressure to bypass theanti-freeflow mechanism 300. In other words, unless the pump is incontrol of the fluid flow, no fluid will flow through the infusion setand a freeflow situation will not develop.

[0083] While the workings of the anti-freeflow mechanism 300 arediscussed in additional detail below, numerous different embodiments ofanti-freeflow mechanisms which can be used with the present inventionare discussed in U.S. patent application Ser. No. 09/569,332, andco-flied U.S. patent application Ser. No. ______ (identified as attorneyfile 0905.ZEVX.CI), both of which are expressly incorporated hearin.

[0084] Once the solution in the tube portion 204 has been driven pastthe anti-freeflow mechanism 300, the solution passes into the proximalend 112 a of the second connector 112. The distal end (downstream) 112 bof the second connector 112 is disposed in engagement with a patientportion of the infusion set (not shown). Typically, the patient portionof the infusion set is slid over the second connector 112 and retainedin a frictional engagement. It can, however, be attached by other means.

[0085] Turning now to FIG. 3, there is shown a bottom view of an enteralfeeding set adaptor 100 having the pump engaging portion 200 of theinfusion set disposed therein for mounting on an infusion pump inaccordance with the principles of the present invention. The centralworking portion 230 of the pump engaging portion 200 extends outwardlyfrom the feeding set adaptor 100 in a loop.

[0086] In the prior art configurations, the portion of the infusion setwhich engages the pump rotor can be stretched unevenly as it is mountedon the pump. This can interfere with monitoring of pressure within theinfusion set. Additionally, stretching the tube and wrapping it aroundthe pump rotor can take some coordination.

[0087] In contrast, the feeding set adaptor 100 and pump engagingportion 200 of the infusion set is loaded by simply engaging the farside of the loop 230 a against the pump rotor and pulling the feedingset adaptor 100 until it can be inserted in the pump. With such aconfiguration, the risk of the central working portion 230 beingstretched unevenly is virtually eliminated. Additionally, it takes verylittle coordination to properly load the feeding set adaptor 100 in thepump. The user simply loops the end 230 a of the looped central workingportion 230 over the rotor and pulls back on the feeding set adaptor 100until it is in alignment with a cavity on the pump, and releases thefeeding set adaptor.

[0088] Turning now to FIG. 4, there is shown a fragmented perspectiveview of an infusion set, generally indicated at 310 and a perspectiveview of a feeding set adaptor 100 and an enteral feeding pump, generallyindicated at 320, made in accordance with principle of the presentinvention. The infusion set 310 includes an inflow tube 314 which istypically connected to a solution container (not shown), such as aplastic bag holding enteral feeding solution, and an outflow tube 318,which is generally connected to an adaptor (not shown) which engages aballoon catheter which traverses the abdominal wall of the patient.

[0089] The inflow tube 314 is connected to the pump engaging portion 200of the infusion set 310 by the first connector 108. As discussed above,the solution passing through the inflow tube 314 and the first connector108 passes through the sample cell 124. Due to the configuration of thefeeding set adaptor 100, the sample cell 124 nests in a channel 324 ofthe infusion pump 320. A portion of the channel 324 defines a housing328 which is preferably made of a generally translucent plastic. Thehousing 328 serves the dual purpose of protecting an optical sensor (notvisible in FIG. 4) from liquids, and of refracting light which isemitted and received by various parts of the optical sensor.

[0090] As the solution passes through the sample cell 124, the opticalsensor sends light through the housing 328 and sample cell 124. Ifliquid is in the sample cell 124, most of the light will travel in sucha path that it is not reflected back to an optical detector. The samplecell 124 is specifically designed so that it always sends some light tothe optical detector to provide an integrity check of the opticalsensor. If a bubble is present, however, a light emitted by the opticalsensor is refracted to the optical detector. The amount of light whichis refracted gives a reliable indication of whether a bubble is present,and the size of the bubble. If the bubble exceeds desired thresholds,the pump 320 can generate an alarm. The alarm may be audible, or simplyappear on a display screen 332 on the pump 320.

[0091] Once the solution has passed through the sample cell 124, itpasses out of the first connector 108 and into the monitoring portion230 of the pump engaging portion 200 of the infusion set 310. Themonitoring portion 234 is disposed between the first and second tubeengagement members 130 and 150, and is disposed in a distal section 324a of the channel 324. Disposed in the walls of the distal section 324 aof the channel 324 is an optical sensor (not shown). The optical sensorsends light between an optical signal emitter and an optical signaldetector. As the monitoring portion 234 of the tube is disposed in thedistal section 324 a of the channel 324, it is positioned to partiallyobstruct the light flow between the optical signal emitter and theoptical signal detector.

[0092] The diameter of the monitoring portion 234 changes as pressurechanges within the tube. The change in diameter of the monitoringportion 234 changes the amount of light which is detected by the opticaldetector and allows the pump 320 to determine pressure within themonitoring portion without direct contact. For example, if the inflowline 314 of the infusion set 310 were to be kinked or otherwiseoccluded, flow through the inflow line would be reduced. As the pumprotor 340 of the infusion pump 320 rotates, it will develop a vacuumupstream from the rotor. Because the inflow line 314 is occluded, thevacuum created by the rotation of the rotor 340 will be greater inmagnitude and will remain longer than if flow through the inflow tubewere not obstructed.

[0093] The vacuum will cause the monitoring portion 234 of the pumpengaging portion 200 to collapse to a greater degree and remain in acollapsed state for a longer period of time. The optical sensor detectsthe collapse because more light will be detected by the optical detectorand for a longer period of time. The pump 320 monitors the readings ofthe optical sensor. If the readings of the optical detector fall outsideof a predetermined range, the pump 320 will generate an alarm indicatingthe presence of an occlusion. It may also automatically stop the pump320 until the occlusion situation has been resolved. A more detaileddiscussion of the interaction between the optical sensor and themonitoring portion 234 of the infusion set 310 is set forth below.Additionally, co-filed U.S. patent application Ser. No. ______(identified as Attorney Docket No. 0908.ZEVX.PT) contains a detaileddiscussion of numerous different applications of such a pressure sensorand is expressly incorporated herein.

[0094] As the solution passes out of the monitoring portion 234, itpasses into the central working portion 230 of the pump engaging portion200 of the infusion set 310. The central working portion 230 is engagedby a plurality of rollers 344 on the pump rotor 340. As the rotor 340rotates, the rollers 344 pinch off sections of the tube and advancetheoretically known volumes of solution with each rotation. (The actualvolumes moved are partially dependent on the pressures on the solutionboth upstream and downstream from the rotor 340). By controlling thenumber of rotations of the rotor 340, and making modifications fordetected pressures, the pump 320 can deliver a known volume of solutionto the patient.

[0095] Once the solution has been moved downstream of the rotor 340, itpasses into the second monitoring portion 260 which is disposed betweenthe third and fourth tube engagement portions 170 and 186. The secondmonitoring portion 260 rests in a channel 354 in the pump 320 which ispreferably disposed parallel to channel 324. The channel 354 also has anoptical sensor which functions in substantially the same manner as thesensor discussed in association with the monitoring portion 234. Theonly signficiant difference between the two is that which the monitoringportion 234 will generally collapse due to vacuum created by the pumprotor 340 and upstream occlusions, the second monitoring portion 260will generally expand due to solution being forced down stream by thepump rotor 340 and any occlusions downstream which inhibit thedownstream flow of solution.

[0096] Once the solution passes out of the second monitoring portion260, it must flow around the anti-freeflow device 300. As mentionedabove, gravity alone is insufficient to develop flow around theanti-freeflow device 300. However, the rotation of the pump rotor 340pushes solution downstream with sufficient force that the tube 204adjacent the anti-freeflow device will expand and create a channelaround the ball 304, thereby allowing the solution to flow down streamto the patient.

[0097] Once past the anti-freeflow device 300, the solution flowsthrough the second connector 112 and into the outflow portion 318 of theinfusion set 310 which delivers the solution to the patient.

[0098] Turning now to FIGS. 5 and 5A, there are shown close-up,cross-sectional views of the feeding set adaptor 100, flexible tubing204 of the pump engaging portion 200 and a portion of the enteralfeeding pump 320 relating to the pressure monitoring mechanismassociated with feeding set adaptor. The enteral feeding pump 320 hastwo channels 324 and 354 which receive the feeding set adaptor 100.

[0099] As shown in FIGS. 5 and 5A, the monitoring portion 230 of theflexible tubing 204 of the pump engaging portion 200 is disposed in thefirst channel 324. Disposed on opposing sides of the first channel 324is an optical sensor 400. The optical sensor includes a optical signalemitter 404 and an optical signal detector 408. Each is provided withleads 412 for communication with the enteral feeding pump.

[0100] In response to an electrical signal from the pump 324, theoptical signal emitter 404 emits light energy, indicated by dashed line420. Those skilled in the art will appreciate that various wavelengthsof light may be used. Currently, it is anticipated that infrared lightwill be preferred.

[0101] The flexible tube 204 forming monitoring portion 230 ispositioned to obstruct some of the light. The extent to which the lightis obstructed, of course, depends on the diameter of the flexible tube204 in the monitoring portion 230. This diameter, depends on thepressure within the tube. Thus, by monitoring the amount of light whichis obstructed, the voltage or other readings of the sensor correlateswith the pressure inside of the tube.

[0102] In a preferred embodiment, the flexible tube 204 forming themonitoring portion 230 is disposed so that it always obstructs somelight, but does not obstruct all light flow between the optical signalemitter and the optical signal detector. This can be used to verify theintegrity of the sensor and proper loading of the tubing. If the opticalsignal detector 408 gives the maximum voltage reading, the tubing 204 isnot loaded properly. If, in contrast, no optical signal is received bythe optical signal detector 408, the sensor 400 is defective and must beserviced or replaced.

[0103] Turning specifically to FIG. 5A, there is shown a view similar tothat of FIG. 5. However, with respect to the monitoring portion 230, thediameter of the tube 204 has decreased. This typically occurs with eachrotation of the pump rotor (FIG. 4) as a temporary vacuum is created assolution is forced through the infusion set. The extent of the vacuumand its duration, however, is related to the presence of occlusions,and/or the viscosity of the solution. The sensor 400 detects the extentof the reduced diameter of the tube 204 in the monitoring portion 230 bythe amount of light received by the optical signal detector 408. Theoptical sensor 400 is thereby able to determine the negative pressurewithin the tube. The pump 320 is then able to make adjustments to rotorrotations to ensure accurate volume delivery. It can also detect anocclusion that should be resolved and generate an alarm.

[0104] The pump 320 also has a second optical sensor 400′ which isdisposed along the second monitoring portion 260 which is down streamfrom the pump rotor (FIG. 4). The sensor 4001 has an optical signalemitter 404 and an optical signal detector 408 which have leads 412 forcommunicating with the pump. The sensor 4001 operates in substantiallythe same manner as the optical sensor 400 and is therefor not discussedin detail.

[0105] One difference between the practical applications of the sensor400′ and sensor 400 is that, because the sensor 400′ is downstream, thesensor 400′ will detect pressure increase in the second monitoringportion 260 with each rotor rotation, instead of the pressure decreasesassociated with the first monitoring portion 230. Thus, as the rotor(FIG. 4) rotates, the pressure in the second monitoring portion 260 willincrease. As shown in FIG. 5A, the increase in pressure causes thediameter of the second monitoring portion to increase and decreasing theamount of light received by the optical signal detector 408.

[0106] The sensor 400′ and monitoring portion 260 can be configured in avariety of ways to achieve the goals of the present invention. In apreferred configuration, the tube 204 is positioned within the sensorsuch that it will always occlude some light, but will never fullyocclude all light from the optical signal emitter 404 to the opticalsignal emitter 408. Thus, a full voltage reading indicates that the tube204 forming the monitoring portion 260 is not properly loaded. A zeroreading indicates that the sensor 400′ has malfunctioned and must beserviced or replaced.

[0107] Between the two extremes is a range of values which correlatewith acceptable pressures which the pump 320 can use to ensure accuracyin volumetric delivery. This is also a threshold which indicates apressure which exceeds acceptable pressure in the infusion set. If thethreshold is surpassed, the pump 320 will generate an alarm and warn theuser that the infusion set is obstructed.

[0108] Those skilled in the art will appreciate that the tube 204 andsensor 400′ could be disposed in communication such that the thresholdpressure occludes all light and therefore generates an alarm. While sucha configuration meets the requirements of generating an alarm and/orshutting off the pump 320 when the pressure is too high, it has thedisadvantage of not distinguishing between a faulty sensor in the pumpand an unacceptably high pressure in the infusion set.

[0109] Those skilled in the art will also realize that numerousmodifications could be made to the presently preferred embodimentdisclosed herein. The sensors need not be disposed adjacent each otherand could be disposed in other locations along an infusion set.

[0110]FIGS. 6 and 6A show a close-up, cross-sectional view of theadaptor and the enteral feeding pump portions relating to the detectionof air bubbles passing through the infusion set. Specifically, thesample cell 124 is disposed in the channel 324 of the pump. The channel324 has a portion 324 b which is defined by a sloped housing 430. Thesloped housing 430 is preferably formed of a clear plastic, such as ABSand has walls 430 a and 430 b which are offset from one another at anangle of between about 45-100 degrees (most preferably about 60degrees), and preferably between 40 and 67.5 degrees from horizontal,and a base 432. The housing also preferably has a flanged portion 434.The housing 430 helps both with bubble detection as explained below, andprevents water or other hazzards from entering the pump 320.

[0111] Disposed adjacent the housing 430 is an optical sensor 440. Theoptical sensor 440 has an optical signal emitter 444 and an opticalsignal detector 448 which are disposed on opposing sides of the housing430. Leads 452 are provided for the optical sensor 440 and pump 320 tosend electronic signals to one another.

[0112] The sample cell 124 is placed in the channel 324 so that it isspaced away from the housing 430 slightly and forms an air chamber 458between the sample cell and housing. While it is preferred that theconduit 460 formed by the sample cell 124 has a cross-section whichforms an inverted equilateral triangle and the sample cell 124preferably has two walls disposed at 60 degrees from one another, thewalls defining the conduit need not form a triangle. As shown in FIG. 6,the walls have a base 464 which is formed at the bottom of the invertedtriangle. Additionally, the top wall 468 could be curved or vaulted toprovide the conduit with a diamond shape. Also, as set forth in moredetail in U.S. patent application Ser. No. ______ (identified asAttorney Docket No. 0906.ZEVX.PT, which is expressly incorporatedherein), numerous different configurations can be used. It is mostdesirable, however, that the sidewalls be disposed at an angle less thannormal to the plane along which the light is emitted to refract thelight back to an optical detector when air is present in the samplecell.

[0113] In use, light is emitted by the optical signal emitter 444 and isrefracted by a sidewall of the housing 430 and again by the air of theair chamber 458. The light is again refracted as it enters into thesidewall 430 a of the housing. If the conduit 460 is filled withsolution, the light undergoes very little refraction as it passes fromthe sidewall 430 a of the housing 430 into the solution. Thus, the lighttravels in a generally straight path which prevents the light fromcontacting the optical signal receiver 448 as shown by the dashed linein FIG. 6.

[0114] If, however, the conduit 460 is filled with air, the differenceindices of refraction of the plastic sample chamber 124 and the air inthe conduit 460 causes the air to be refracted to a much greater degreeas shown by the upper dashed line in FIG. 6A. The light is thenrefracted again as it passes from the air in the conduit to the opposingsidewall 430 b, through the air chamber 458 and through the housing 430.The refraction is such that the light is directed to the optical signaldetector 448. If an air bubble is present in the conduit 460, it willdirect an increased amount of light to the optical signal detector 448.The amount of light refracted to the optical signal detector 408 isproportional to the size of the air bubble. Thus, the voltage readingobtained from the optical signal detector 448 is proportional to thesize of the bubble.

[0115] The base 464 of the sample cell 124 assists in the important roleof integrity checking the optical sensor 440. The base 464 is positionedso that it will always allow some light through to impact the opticalsignal detector 448 as shown by the lower dashed line in FIG. 6A. Thus,if the optical signal detector 448 indicates a reading of zero, an alarmcan be generated indicating that the sensor 440 has failed. Likewise,the refraction of light is controlled so that too high of a readingindicates that the sample cell 124 has not been properly loaded in thechannel 324.

[0116] Turning now to FIGS. 7 and 7A, there are shown close-up,cross-sectional views of the feeding set adaptor 100 and the pumpengaging portion 200 of the infusion set 310 as they relate to theanti-freeflow mechanism 300 of the present invention. It is important toprevent an infusion set from providing uncontrolled solution to thepatient. While many enteral feeding systems have roller clamps or otherpinch clip occluders, most devices do not affirmatively prevent fluidflow when the pump is not controlling the flow. In contrast, theanti-freeflow mechanism 300 only allows fluid flow when the pump isactively driving solution through the system.

[0117] The anti-freeflow mechanism shown in FIGS. 7 and 7A is a smallsubstantially ball-shaped member 304 which is sized slightly larger thanthe inside diameter of the flexible tube 204 which forms the pumpengaging portion 200 of the infusion set 310. As such, the ball-shapedmember 304 prevents fluid flow under gravity pressures. If, however, apressure well above that caused by gravity is developed in the flexibletube 204, the flexible tube will expand and develop a channel 480 aboutthe exterior of the ball-shaped member 304. (It will be appreciated thatother shapes may also be used).

[0118] The channel 480 is opened each time the pump rotor drivessolution through the pump engaging portion 200 of the infusion set 310and allows solution to flow downstream. Unlike other clamps which aremanually controlled or which open by closing of the pump housing, theconfiguration is advantageous because it will not allow a freeflowcondition to develop, even if the feeding set adaptor 100 is properlymounted in the pump 320 and the pump engaging portion 200 of theinfusion set 310 has simply been pulled out of engagement with the pumprotor.

[0119] Turning now to FIG. 7B, there is shown a cross-sectional view ofthe adaptor 100, pump engaging portion 200 of the infusion set 310 andenteral feeding pump 320 providing an alternate embodiment of theanti-freeflow mechanism of the present invention. While the embodimentdiscussed with respect to FIGS. 7 and 7A is presently preferred, theremay be situations in which it is not desired to force the solution toopen a channel around the anti-freeflow mechanism. In such situations,the channel can be opened by interaction of a pump cover 500, theanti-freeflow mechanism 300 and the channel 354 of the pump 320. Thecover 500 preferably has an engagement member 504 which is configured toforcefully engage the flexible tube on the opposite side of the tubefrom the anti-freeflow mechanism. The channel 354 also may have a stop510 which engages the outside of the flexible tube 204 opposite theanti-freeflow mechanism 300.

[0120] As the flexible tubing 204 gets compressed between the engagementmember 504 and the anti-freeflow mechanism 300 and between the stop 510and the anti-freeflow mechanism, the flexible tubing will bow outwardlyalong the sides of the anti-freeflow mechanism 300 and form channels forthe solution to flow around the anti-freeflow mechanism. Thus, once thecover 500 is closed and secured, solution flow passed the anti-freeflowmechanism 300 can occur regardless of whether the pump rotor 340 isproperly engaging the pump engaging portion 200 of the infusion set 310.

[0121] Turning now to FIG. 7C, there is shown a close-up,cross-sectional view of yet another embodiment of the anti-freeflowmechanism 300′ of the present invention. Instead of using a ball-shapedmember 304 inside of the tube, the embodiment shown in FIG. 7C shows aflap 304′ which is disposed in the connector 112. The flap is configuredto substantially prevent fluid flow through the connector if pressuresare equal to or less than typically encountered due to gravity. If adesired pressure threshold is passed, the flap 304′ is forced open andallows solution to flow down stream. Those skilled in the art willappreciate that the flap 304′ could be configured to remain open oncedeflected by the solution pressure, or could be mounted such that theflap 304′ returns to its original position once the solution pressuresare insufficient to hold the flap open.

[0122] Thus there is disclosed an improved feeding set adaptor. Theadaptor enables the integration of the various functions discussedabove, and provides improved pressure monitoring, anti-freeflow andbubble detection at a price well below the systems of the prior art.Additionally, the feeding set adaptor increases the ease of loading andunloading the tube engaging portion of the infusion set. While numerousdifferent embodiments of the present invention have been disclosed,those skilled in the art will appreciate numerous modifications whichcan be made without departing from the scope and spirit of the presentinvention. The appended claims are intended to cover such modifications.

What is claimed is:
 1. A feeding set adaptor comprising: a firstconnector configured for attachment to an inflow line of an infusion setand a central pump engaging portion of an infusion set; a secondconnector configured for attachment to an outflow line of an infusionset; and an anti-freeflow mechanism disposed in communications with theone of the first connector and the second connector.
 2. The feeding setadaptor according to claim 1, wherein the anti-freeflow mechanism isattached to and spaced apart from one of the first connector and thesecond connector.
 3. The feeding set adaptor according to claim 1,wherein the anti-freeflow mechanism comprises a generally ball-shapedmember configured for disposition in the tubing of an infusion set. 4.The feeding set adaptor according to claim 3, wherein the ball-shapedmember is attached to one of the first connector and the secondconnector and spaced away from the connector to which the ball-shapedmember is attached so that a flow channel may be formed around theball-shaped member and into the connector to which the ball-shapedmember is attached.
 5. A solution delivery system for disposal on aninfusion pump comprising the feeding set adaptor according to claim 1,and further comprising an inflow line, a pump engaging portion, and anoutflow line attached to the feeding set adaptor.
 6. The solutiondelivery system according to claim 5, wherein the anti-freeflowmechanism is disposed in one of the inflow line, pump engaging portionand outflow line.
 7. The solution delivery system according to claim 6,wherein the anti-freeflow mechanism is attached to the second connectorand disposed in the pump engaging portion of the infusion set.
 8. Thesolution delivery system according to claim 7, wherein the outsidediameter of the anti-freeflow mechanism is slightly larger than theinside diameter of the pump engaging portion of the infusion set.
 9. Thesolution delivery system according to claim 5, wherein the anti-freeflowmechanism is a generally ball-shaped member.
 10. The solution deliverysystem according to claim 5, wherein the pump engaging portion comprisesat least one monitoring portion for optically monitoring pressure withinthe infusion set.
 11. The solution delivery system according to claim10, wherein the pump engaging portion further comprises at least oneabutment member for engaging the feeding set adaptor to minimizemovement of the monitoring portion when the pump engaging portion isworked by a pumping mechanism.
 12. The solution delivery systemaccording to claim 11, further comprising an optical sensor disposedadjacent to the monitoring portion for determining pressure in themonitoring portion.
 13. The solution delivery system according to claim12, wherein the optical sensor comprises an optical signal emitter andan optical signal emitter and an optical signal detector, and wherein atleast a portion of the monitoring portion is disposed between theoptical signal emitter and the optical signal detector.
 14. The solutiondelivery system according to claim 13, wherein the monitoring portion isdisposed between the optical signal emitter and the optical signaldetector, so that it always occludes some light flow between the opticalsignal emitter and the optical signal detector.
 15. The solutiondelivery system according to claim 13, wherein the monitoring portion isdisposed between the optical signal emitter and the optical signaldetector, so that it always allows some light flow between the opticalsignal emitter and the optical signal detector.
 16. The solutiondelivery system according to claim 11, wherein the feeding set adaptorhas at least one tube engaging member and wherein the abutment member ofthe pump engaging portion engages the tube engagement member of thefeeding set adaptor to limit movement of the pump engagement portion.17. The solution delivery system according to claim 16, wherein the atleast one tube engaging member defines a recess, and wherein theabutment member comprises a collar configured for resting in the recess.18. The solution delivery system according to claim 16, wherein the atleast one tube engagement member comprises a first tube engagementmember and a second tube engagement member disposed adjacent to eachother with the monitoring portion extending therebetween.
 19. Thesolution delivery system according to claim 18, wherein the pumpengagement portion has a first abutment member disposed to engage thefirst tube engaging member and a second abutment member disposed toengage the second tube engaging member, the two abutment members beingspaced apart and a distance therebetween constituting the monitoringportion of the pump engaging portion of the infusion set.
 20. Thesolution delivery system according to claim 18, wherein the at least onetube engagement member further comprises a third tube engagement memberand a fourth tube engagement member disposed adjacent to each other, andthe pump engaging portion of the infusion set forming a secondmonitoring portion extending between the third tube engagement memberand the fourth tube engagment member.
 21. The solution delivery systemaccording to claim 16, wherein the at least one tube engaging member andthe at least one monitoring portion comprise a first monitoring portionand at least one tube engagement configured for disposition upstreamfrom a pump rotor, and a second monitoring portion and at least one tubeengagement member configured for disposition downstream from a pumprotor.
 22. The feeding set adaptor according to claim 1, furthercomprising a sample cell formed as part of the adaptor.
 23. The feedingset adaptor according to claim 22, wherein the sample cell has a pair ofside walls disposed at an angle between about 45 and 100 degrees fromone another.
 24. The feeding set adaptor according to claim 23, whereinthe sample cell defines a conduit having at least two sides which aredisposed at an angle of about 50 to 60 degrees from one another.
 25. Thefeeding set adaptor according to claim 24, wherein the conduit has across-section which is an equilateral triangle.
 26. The feeding setadaptor according to claim 25, wherein the conduit has a cross-sectionwhich is an inverted equilateral triangle, the sides extendingdownwardly and inwardly.
 27. The feeding set adaptor according to claim24, wherein the conduit has a cross-section which is diamond shaped. 28.The feeding set adaptor according to claim 22, wherein the sample cellhas an outer wall which extends toward point, and a generally linearbase extending outwardly from the point and disposed to allow light toflow through the base with minimal refraction.
 29. A solution deliverysystem comprising the feed set adaptor according to claim 22, andfurther comprising a housing disposed adjacent to the sample cell. 30.The solution delivery system according to claim 29, wherein the housingis spaced apart from the sample cell so as to form an air chamberbetween the housing and the sample cell.
 31. The solution deliverysystem according to claim 29, wherein the housing has a pair ofsidewalls which are disposed at an angle of between about 45 and 100degrees from one another.
 32. The solution delivery system according toclaim 31, wherein the housing further comprises a base disposed at anangle of about 50 to 60 degrees from each of the sidewalls.
 33. Asolution delivery system comprising the feed set adaptor according toclaim 22, and further comprising a optical sensor disposed to projectlight into the sample cell.
 34. The solution delivery system accordingto claim 33, wherein the optical sensor comprises an optical signalemitter and an optical signal detector, and wherein the sample cell isdisposed between the optical signal emitter and the optical signaldetector.
 35. The solution delivery system according to claim 35,wherein the sample cell is configured to direct more light emitted fromthe optical signal emitter to the optical signal detector when thesample cell is at least partially filled with air.
 36. A feeding setadaptor configured for mounting on an infusion pump, the feeding setadaptor comprising a connector for connecting an inflow tube and a pumpengaging tube of an infusion device, and a sample cell configured foroptically detecting air bubbles within the sample cell.
 37. The feedingset adaptor according to claim 36, wherein the sample cell comprises atleast two side walls disposed at an angle of between about 45 and 100degrees to one another.
 38. The feeding set adaptor according to claim37, wherein the sample cell comprises an equilateral triangle, withsidewalls disposed at an angle of about 50 to 60 degrees from oneanother.
 39. The feeding set adaptor according to claim 38, wherein thesample cell further comprises a base disposed at one corner of theequilateral triangle.
 40. The feeding set adaptor according to claim 36,wherein the sample cell defines a conduit which has a cross-section ofan inverted equilateral triangle.
 41. A solution delivery systemincluding the feeding set adaptor according to claim 36, and furthercomprising an optical sensor disposed adjacent the sample cell.
 42. Thesolution delivery system according to claim 41, wherein the opticalsensor includes an optical signal emitter and an optical signal detectorplaced generally on opposing sides of the sample cell.
 43. The solutiondelivery system according to claim 41, wherein the sample cellconfigured such that when disposed between the optical signal emitterand the optical signal detector, the sample cell will dispel some lightemitted by the optical signal detector so that said light does not reachthe optical signal detector.
 44. The solution delivery system accordingto claim 41, wherein the sample cell is configured so that some lightfrom the optical signal emitter will always reach the optical signaldetector when the sample cell is disposed between the optical signalemitter and the optical signal detector.
 45. The solution deliverysystem according to claim 44, wherein the sample cell comprises a baseportion configured to channel light emitted by the optical signalemitter to the optical signal detector regardless of whether the samplecell is full or air or liquid.
 46. The solution delivery systemaccording to claim 41, wherein the system further comprises a housingdisposed between the optical signal sensor and sample cell.
 47. Thesolution delivery system according to claim 46, wherein the housing hasa pair of sidewalls disposed at an angle of between about 45 and 100degrees relative to one another.
 48. The solution delivery systemaccording to claim 47, wherein the housing and the sample cell each haveside walls disposed at an angle of about 60 degrees to one anther andwherein said sidewalls of the sample cell are disposed in parallel tothe sidewalls of the housing.
 49. The solution delivery system accordingto claim 46, wherein the housing and the sample cell are spaced apart todefine an air chamber therebetween.
 50. The solution delivery systemaccording to claim 46, wherein the sample cell has a base and whereinthe housing has a base disposed generally parallel to the base of thesample cell.
 51. The solution delivery system according to claim 46,wherein the optical sensor and the housing are formed as part of aninfusion pump.
 52. The feeding set adaptor according to claim 36,wherein the feeding set adaptor has a second connector for connectingthe pump engaging portion to an outflow line of an infusion set.
 53. Thefeeding set adaptor according to claim 36, wherein the adaptor furthercomprises at least one tube engagement member configured for engaging apump engaging portion of an infusion set.
 54. A solution delivery systemhaving the feeding set adaptor according to claim 53, and furthercomprising a flexible tube attached to the feeding set adaptor, theflexible tube forming a pump engaging portion of an infusion set. 55.The solution delivery system according to claim 54, wherein the pumpengaging portion of the infusion set has an abutment member for engagingthe at least one tube engagement member.
 56. The solution deliverysystem according to claim 55, wherein the feeding set adaptor has atleast two tube engagement members and wherein the pump engagementportion of the infusion set has a central working portion and at leasttwo abutment members, one being disposed adjacent opposing ends of thecentral working portion and configured to engage the tube engagementmembers.
 57. The solution delivery system according to claim 56, whereinthe system further comprises an enteral feeding pump with a rotor, andwherein at least one tube engagement member and at least one abutmentmember is disposed on the upstream side rotor and at least one tubeengagement member and at least one abutment member is disposed on adownstream side of the rotor.
 58. The solution delivery system accordingto claim 57, further comprising an optical sensor disposed adjacent theat least one tube engagement member disposed upstream from the rotor andconfigured to detect pressure in a flexible tube forming the pumpengagement portion of an infusion set adjacent said at least one tubeengagement member.
 59. The solution delivery system according to claim57, further comprising an optical sensor disposed adjacent the at leastone tube engagement member disposed downstream from the rotor andconfigured to detect pressure in the in a flexible tube forming the pumpengagement portion of an infusion set adjacent said at least one tubeengagement member.
 60. The solution delivery system according to claim55, wherein the tube engagement member defines a recess, and wherein theabutment member is received in the recess.
 61. The solution deliverysystem according to claim 60, wherein the adaptor has a first tubeengagement member and a second tube engagement member and wherein thepump engaging portion has a first abutment member which engages thefirst tube engagement member and a second abutment member which engagesthe second tube engagement member, and a space between the first andsecond abutment members forming a monitoring portion.
 62. The solutiondelivery system according to claim 61, wherein the system furthercomprises an optical sensor disposed adjacent the monitoring portion andconfigured to measure expansion and contraction of the monitoringportion.
 63. The solution delivery system according to claim 61, whereinthe adaptor has a third tube engagement member and a fourth tubeengagement member and wherein the pump engaging portion has a thirdabutment member which engages the third tube engagement member and afourth abutment member which engages the fourth tube engagement member,and a space between the third and fourth abutment members forming amonitoring portion.
 64. The solution delivery system according to claim63, wherein the system further comprises an optical sensor disposedadjacent the monitoring portion between the third and fourth abutmentmembers and configured to measure expansion and contraction of saidmonitoring portion.
 65. The solution delivery system according to claim64, further comprising a means for generating an alarm when a pressurein a monitoring portion falls outside a predetermined range.
 66. Afeeding set adaptor for use with an infusion set, the feeding setadaptor having at least two tube engagement members configured forreceiving and engaging a pump engaging portion of an infusion set, atleast one of the at least two tube engagement members being configuredfor engaging an upstream portion of the pump engaging portion and atleast one of the at least two tube engagement members being configuredfor engaging a downstream portion of the pump engaging portion.
 67. Thefeeding set adaptor according to claim 66, wherein the tube engagementmembers comprise flanges for securing the pump engagement portion. 68.The feeding set adaptor according to claim 66, further comprising afirst connector configured for attachment to an inflow line of aninfusion set and a second connector configured for attachment to anoutflow line of an infusion set.
 69. The feeding set adaptor accordingto claim 66, wherein the feeding set adaptor further comprises ananti-freeflow mechanism.
 70. The feeding set adaptor according to claim69, wherein the anti-freeflow mechanism comprises a stop sized fordisposition inside a tube of an infusion set.
 71. The feeding setadaptor according to claim 69, wherein the anti-freeflow adaptorcomprises a flap.
 72. A solution delivery system including a feeding setadaptor in accordance with claim 66, further comprising a flexible tubeforming a pump engaging portion of an infusion set.
 73. The solutiondelivery system according to claim 72, wherein the flexible tube engagesthe tube engagement members and forms at least one monitoring portion.74. The solution delivery system according to claim 73, wherein theflexible tube has a first monitoring portion and a second monitoringportion.
 75. The solution delivery system according to claim 74, whereinthe system further comprises a pumping mechanism and wherein the firstmonitoring portion is disposed upstream from the pumping mechanism andthe second monitoring portions is disposed downstream from the pumpingmechanism.
 76. The solution delivery system according to claim 74,wherein the feeding adaptor has a first tube engagement member and asecond tube engagement member spaced apart from one another, and whereinthe first monitoring portion is disposed between the first and secondtube engagement members.
 77. The solution delivery system according toclaim 76, wherein the flexible tube has a first abutment member and asecond abutment member for engaging the first tube engagement member andthe second tube engagement member, respectively, to thereby limit axialmovement of the flexible tube.
 78. The solution delivery systemaccording to claim 76, further comprising an optical sensor disposedadjacent the first and second tube engagement members.
 79. The solutiondelivery system according to claim 76, wherein the feeding set adaptorhas a third tube engagement member and a fourth tube engagement memberand wherein the flexible tube has a third abutment member and a fourthabutment member for engaging the third tube engagement member and thefourth tube engagement member, respectively, to thereby limit axialmovement of the flexible tube.
 80. The feeding set adaptor according toclaim 66, further comprising a sample cell.
 81. The feeding set adaptoraccording to claim 80, wherein the feeding set adaptor has a firstconnector and a second connector and wherein the sample cell is disposedin one of the first and second connectors.
 82. The feeding set adaptoraccording to claim 80, wherein the sample cell has a pair of sidewallsdisposed at an angle of between about 45 and 100 degrees from oneanother.
 83. The feeding set adaptor according to claim 82, wherein thesample cell has a base portion configured for transmitting lightregardless of the contents of the sample cell.
 84. A solution deliverysystem according to claim 82, further comprising a housing disposedadjacent the sample cell.
 85. The solution delivery system according toclaim 84, wherein the housing has a pair of sidewalls disposed at anangle of 50 to 60 degrees from one another.
 86. A solution deliverysystem according to claim 82, further comprising an optical sensordisposed to transmit light into and detect light refracted in the samplecell.
 87. A method for forming an infusion set, the method comprising;selecting a feeding set adaptor having a first connector and a secondconnector formed integrally together; attaching an infusion set inflowline to the first connector; attaching an infusion set outflow line tothe second connector; and attaching a pump engaging portion of aninfusion set to the first and second connectors so that the inflow line,the pump engaging portion and the outflow line are in fluidcommunication with one another.
 88. The method according to claim 87,wherein the method comprises selecting a feeding set adaptor having ananti-freeflow mechanism.
 89. The method according to claim 87, whereinthe method comprises selecting a feeding set adaptor having a samplecell formed thereon.
 90. The method according to claim 87, wherein themethod comprises attaching the pump engaging portion to th e feeding setadaptor to form at least one monitoring portion which has limited axialmovement.
 91. A method for monitoring pressure in an infusion set, themethod comprising: selecting a feeding set adaptor having a pumpengaging portion of an infusion set disposed thereon and defining amonitoring portion; and disposing the monitoring portion in an opticalsensor to detect pressure changes in the monitoring portion by changesin the diameter of the monitoring portion.
 92. A method for preventingfreeflow in an infusion set, the method comprising: selecting a feedingset adaptor having a pump engaging portion of an infusion set disposedthereon and defining a monitoring portion and an anti-freeflow mechanismconfigured to selectively stop fluid flow through the infusion set; anddisposing the anti-freeflow mechanism in the infusion set to selectivelypreclude fluid flow therethrough.
 93. A method for detecting air bubblespassing through an infusion set, the method comprising; selecting afeeding set adaptor having a sample cell formed thereon and having apump engaging portion attached thereto; passing solution through thesample cell; and disposing the sample cell in an optical signal suchthat light is refracted differently when air is present in the samplecell than when solution is present in the sample cell to therebydetermine the presence of air.
 94. The method according to claim 93,wherein the method comprises emitting the light in a plane andpositioning the sample cell so that a sidewall of the sample cell is atan angle less than normal to the plane.